A triprotic acid, H3A, has three ionization constants of Ka1= 8.7x10^-3, Ka2= 1.9x10^-8, and Ka3=8.6x10^-13 for the steps respectively. the following reaction represents the reactions that would take place during titration of this acid with a strong base. Using Kw and Ka values above, determine the equillibrium constant for the following three steps.
H3A + OH- === H2A- + H2O : K'=
H2A- + OH- === HA^2- + H2O : K"=
HA^2- + OH- === A^3- + H2O : K'"=